Thermal Load in Large-Scale Bridges: A State-of-the-Art Review

Thermal load is an important factor that must be taken into account during the procedure of bridge design and structural condition evaluation especially for those statically indeterminate bridges and cable-supported bridges. This paper presents an overview of current research and development activities in the field of thermal load in bridge, in which emphasis is placed on the thermal load models established by numerical analysis and field measurement. The theoretical formulations and boundary conditions of heat transfer in bridge are firstly outlined. And then, the states of the art of numerical solutions for temperature distribution in bridge including finite difference method and finite element method are reviewed in detail. Following that, the progress on thermal load in three types of representative bridges that are concrete bridge, steel-concrete composite bridge, and steel bridge based on field measurement data is discussed extensively. Finally, some existing problems and promising research efforts about thermal load in bridge are remarked. 1. Introduction Different forms of bridges, such as cable-supported bridge, arch bridge, multispan continuous bridge and simple supported bridge, which are key elements of the highway infrastructure, have been built throughout the world to fulfill the requirements of modern society for advanced transportation [1–4]. Recent advances of design methodologies and construction technologies have made it possible to construct bridges with great size. Up to now, the span of bridge exceeds 1900？m, and the depth and the width of the box girder are more than 13？m and 35？m, respectively [5–7]. It is well known that the service life of those bridges almost exceeds 50 years or even 100 years sometimes. During the lifetime, it is inevitable that bridges are subjected to daily, seasonal, and yearly repeated cycles of heating and cooling induced by solar radiation and surrounding air. The up and down temperatures in structural components may cause nonlinear thermal load that influences the performance of bridges significantly. In practice, the variation of temperatures affects bridges in a complicated manner. From the point of view of global response, uniform temperature changes cause large overall expansion and contraction in bridge components. On one hand, the deformation induces the shift of structural dynamic characteristics, which has significant influence on the results of damage identification using vibration-based methods. Researchers from Los Alamos National Laboratory found that the first three natural frequencies of